2021-08-02. ‘Totally new’ idea suggests longer days on early Earth set stage for complex life. By Elizabeth Pennisi, Science Magazine. Excerpt: Today, oxygen fuels much of life on Earth, but it wasn’t always that way. Three billion years ago, this gas was scarce in the atmosphere and oceans. Knowing why oxygen became plentiful could illuminate the evolution of our planet’s flora and fauna, but scientists have struggled to find an explanation satisfying to all. Now a research team has proposed a novel link between how fast our planet spun on its axis, which defines the length of a day, and the ancient production of additional oxygen. Their modeling of Earth’s early days, which incorporates evidence from microbial mats coating the bottom of a shallow, sunlit sinkhole in Lake Huron, produced a surprising conclusion: as Earth’s spin slowed, the resulting longer days could have triggered more photosynthesis from similar mats, allowing oxygen to build up in ancient seas and diffuse up into the atmosphere. That proposal, described today in Nature Geoscience, has intrigued some scientists. “The rise of oxygen [on Earth] is easily the most substantial environmental change in the history of our planet,” says Woodward Fischer, a geobiologist at the California Institute of Technology who was not involved with the work. This study offers “a totally new flavor of an idea. It’s making a connection that people haven’t made before.”... [https://www.sciencemag.org/news/2021/08/totally-new-idea-suggests-longer-days-early-earth-set-stage-complex-life] 2021-02-25. The first organism to use oxygen may have appeared surprisingly early. By Robert F. Service, Science Magazine. Excerpt: The first organisms to “breathe” oxygen—or at least use it—appeared 3.1 billion years ago, according to a new genetic analysis of dozens of families of microbes. The find is surprising because the Great Oxidation Event, which filled Earth’s atmosphere with the precious gas, didn’t occur until some 500 million years later.... [https://www.sciencemag.org/news/2021/02/first-organism-use-oxygen-may-have-appeared-surprisingly-early] 2013-10-03. The Mystery of Earth’s Oxygen. Excerpt: Donald E. Canfield...and his colleagues have published a pair of studies that provide significant clues about some of the most important chapters in oxygen’s history. They’re finding that our weirdly oxygen-rich atmosphere is the result of a complicated dance of geology and biology. ...the earth started out with an oxygen-free atmosphere. It took billions of years before there was enough of it to keep animals like us alive. ...the atmosphere three billion years ago had only 0.03 percent of today’s oxygen levels. ...some microbes had evolved the ability to carry out photosynthesis.... They gave off oxygen as waste. Much of the oxygen released by these photosynthetic microbes was sucked out of the atmosphere by the earth’s vacuum. When microbes died, oxygen reacted with their carbon.... In his forthcoming book, “Oxygen: A Four Billion Year History,” Dr. Canfield suggests that this weak vacuum drove a sudden climb in oxygen that geochemists see in rocks from about 2.3 billion years ago. “Now we get to the point where the earth has calmed down enough that the balance has tipped in the favor of oxygen,” he said. ...Reporting last week in The Proceedings of the National Academies of Sciences, Dr. Canfield and his colleagues report that there was so much oxygen in the atmosphere that it penetrated down a thousand feet into the ocean. Dr. Canfield speculates that oxygen may have become as abundant as it is today, at least for a while. ...Life and earth have continued to twiddle the oxygen knob over the past two billion years. When plants evolved, for example, they began storing huge amounts of carbon in wood and other tough tissues, leaving less to react with oxygen and pull it out of the atmosphere. By 300 million years ago, oxygen had risen to levels as high as 50 percent higher than today. But as continents moved across the globe, the planet’s geography came to favor deserts. Forests shrank, bringing down the oxygen levels.... http://www.nytimes.com/2013/10/03/science/earths-oxygen-a-mystery-easy-to-take-for-granted.html. Carl Zimmer, The New York Times.
2012 Mar 18. Archaean Haze | Nature Geoscience Press Release. Excerpt: The Earth's atmosphere periodically transitioned between a hydrocarbon haze and haze-free conditions 2.65–2.5 billion years ago, reports a paper published online this week in Nature Geoscience. The haze permanently retreated following the oxygenation of the atmosphere approximately 100 million years later…. (See also: http://newswatch.nationalgeographic.com/2012/03/19/early-earth-turned-methane-haze-on-and-off/) 2009 March 25. Deep-sea
Rocks Point To Early Oxygen On Earth. Science
Daily. Excerpt: Red
jasper cored from layers 3.46 billion years
old suggests that not only did the oceans contain
abundant oxygen then, but that the atmosphere
was as oxygen rich as it is today, according
to geologists.
This jasper or hematite-rich chert formed in
ways similar to the way this rock forms around
hydrothermal vents in the deep oceans today.
...The researchers drilled diagonally into the
base of a hill in the Pilbara Craton in northwest
Western Australia to obtain samples of jasper
that could not have been exposed to the atmosphere
or water. These jaspers could be dated to 3.46
billion years ago.
"Everyone agrees that this jasper is 3.46
billion years old," said Hiroshi Ohmoto,
professor of geochemistry, Penn State. "If
hematite were formed by the oxidation of siderite
at any time, the hematite would be found on
the outside of the siderite, but it is found
inside," he reported in a recent issue
of Nature Geoscience.
...said Ohmoto, "It also means that there
was oxygen in the atmosphere 3.46 billion years
ago, because the only mechanism for oxygen to
exist in the deep oceans is for there to be
oxygen in the atmosphere."
In fact, the researchers suggest that to have
sufficient oxygen at depth, there had to be
as much oxygen in the atmosphere 3.46 billion
years ago as there is in today's atmosphere.
To have this amount of oxygen, the Earth must
have had oxygen producing organisms like cyanobacteria
actively producing it, placing these organisms
much earlier in Earth's history than previously
thought....
27 September 2007 NASA RELEASE: 07-215 - NASA
RESEARCH INDICATES OXYGEN ON EARTH 2.5 BILLION
YEARS AGO. Excerpt:
MOFFETT FIELD, Ca lif. -
NASA-funded astrobiologists have found evidence
of oxygen present in Earth's atmosphere earlier
than previously known, pushing back the timeline
for the rise of oxygen in the atmosphere. Two
teams of researchers report that traces of oxygen
appeared in Earth's atmosphere from 50 to 100
million years before what is known as the Great
Oxidation Event. This event happened between
2.3 and 2.4 billion years ago, when many scientists
think atmospheric oxygen increased significantly
from the existing very low levels.
Scientists analyzed a kilometer-long drill core
from Western Australia, representing the time
just before the major rise of atmospheric oxygen.
They found evidence that a small but significant
amount of oxygen was present in Earth's oceans
and atmosphere 2.5 billion years ago. The findings
appear in a pair of research papers in the Sept.
28 issue of the journal Science.
"We seem to have captured a piece of time
during which the amount of oxygen was actually
changing -- caught in the act, as it were," said
Ariel Anbar, an associate professor at Arizona
State University, Tempe, and leader of one of
the research teams.
...One possible explanation for the Great Oxidation
Event is the ancient ancestors of today's plants
first began to produce oxygen by photosynthesis.
However, many geoscientists think organisms
began to produce oxygen much earlier, but the
oxygen was destroyed in reactions with volcanic
gases and rocks.
..."What we have now is new evidence for
some oxygen in the environment 50 to 100 million
years before the big rise of oxygen," Anbar
said. "Our findings strengthen the notion
that organisms learned to produce oxygen long
before the Great Oxidation Event, and that the
rise of oxygen in the atmosphere ultimately
was controlled by geological processes."
...For more information about the NASA Astrobiology
Institute, visit:
http://nai.nasa.gov
3 February 2004. When
Giants Had Wings and 6 Legs. By HENRY
FOUNTAIN, New York Times. Before
the dinosaurs, it was the insects that were
huge. Why? It may have been the air.... There
was an array of giant flightless insects,
and a five-foot-long millipede-like creature,
Arthropleura, that resembled a tire tread
rolled out flat. But perhaps the most remarkable
of all were the giant dragonflies, Meganeuropsis
permiana and its cousins, with wingspans that
reached two and a half feet. They were the
largest insects that ever lived. These large
species thrived about 300 million years ago,
when much of the land was lush and tropical
and there was an explosion of vascular plants
(which later formed coal, which is why the
period is called the Carboniferous). But the
giant species were gone by the middle to late
Permian, some 50 million years later. Scientists
have long suspected that atmospheric oxygen
played a central role in both the rise and
fall of these organisms. Recent research on
the ancient climate by Dr. Robert A. Berner,
a Yale geologist, and others reinforces the
idea of a rise in oxygen concentration - to
about 35 percent, compared with 21 percent
now - during the Carboniferous. Because of
the way many arthropods get their oxygen,
directly through tiny air tubes that branch
through their tissues rather than indirectly
through blood, higher levels of the gas might
have allowed bigger bugs to evolve.... "It's
been out there in the literature for a long
time without a causal mechanism," said
Dr. Robert Dudley, a professor at the University
of California at Berkeley who has studied
the effects of elevated oxygen pressures on
modern insects. ...Dr. Jon F. Harrison, a
professor at Arizona State ... said, "It's
still in the realm of speculation."
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